METHODS OF INVESTIGATION. 129 



the prosecution of investigations which may be productive of great 

 results to pathology, if an experimentalist were desirous of analys- 

 ing exudations in accordance with the points of view we have been 

 considering, he would of course feel the want of the necessary ma- 

 terial in the neighbourhood of merely a small hospital ; for in every 

 case the investigation should begin with the most recent exudations, 

 and it is precisely these which are the most rarely met with. In 

 addition to the age of the exudation, other points have also to be 

 observed ; for the exudative matters yielded by similar cavities and 

 tissues, ought to be compared together, which it would not be easy 

 to do in small establishments, whilst the accompanying morbid 

 processes, to which the physician attaches the greatest weight, ought 

 to be noted, together with the stages of the exudation and the 

 cavities or organs in which the effusion occurs ; but for these pur- 

 poses we require a larger amount of materials than can often be 

 obtained. If, moreover, the chemist should have the misfortune 

 to be associated with physicians who have a prejudice against 

 venesection, however much theory and practice may favour its 

 adoption, he will be compelled to relinquish the examination of 

 the exudations, for unless he has obtained a previous blood- 

 analysis, such an investigation will be of no value. One of the 

 greatest difficulties which present themselves in the way of obtain- 

 ing materials necessary for these observations is the circumstance 

 that either from regulations connected with medical jurisprudence, 

 feelings of humanity, or other considerations, examinations are 

 not undertaken until twenty-four hours, or even a longer interval 

 after death, a period within which various processes of decom- 

 position may have set in, and the alterations produced by death 

 may have attained a very high degree of intensity by diffusion and 

 endosmosis. Many of these impediments might be obviated by 

 conducting such experiments as we have described in the neigh- 

 bourhood of large veterinary institutions, and indeed the advan- 

 tages of employing diseased animals for such investigations are so 

 obvious that it seems wholly superfluous to refer more fully to 

 them in the present place. Unfortunately, however, very few patho - 

 logico-chemical investigations have been prosecuted in institu- 

 tions of this kind ; we must hope, however, that they may speedily 

 be made to contribute towards the establishment of a rational 

 pathological chemistry, since institutions of this class afford much 

 more abundant available materials than hospitals even, for the 

 analyses of the blood. Some of the principal difficulties which we 

 have enumerated present themselves even when we have an abun- 

 VOL. in. K 



